The 50-page document, discovered in an abandoned bank in LA, includes claims that Chaplin first seduced the actress when she was 15 and he was 35.

Chaplin had known Grey since she was 8, and a few years later she appeared in his movie “The Kid.”

After she became pregnant at 16 and refused his demand to have an abortion, her mother allegedly threatened to report Chaplin to police unless he married her.

They wed in 1924 when she was still only 16.

She also claimed Chaplin made “revolting, degrading and offensive” sexual demands and forced her to perform acts that were illegal in California in the 1920s, which he said he had performed with “five prominent moving-picture women” before their marriage.

One of those desires was that Grey take part in a threesome with another woman.

The shocking details helped Grey land the world’s then-largest divorce settlement of $825,000.

John Cabello, owner of UK company Parade Antiques, which is selling the document, said: “We got it from a person in America who was told to clear out old documents at the bank. He was told they would be thrown away, and he kept them instead.”

Grey went on to marry three more times and died in 1995.

Chaplin wed twice again and died in 1977 at age 88 claimed to have had sexual relations with more than 2,000 women.